 element library { 
  element book {
   attribute id {text},
   attribute available {text},
   attribute dimensions {list {token, token, token, ("inches"|"cm"|"mm")}},
   element isbn {text},
   element title {attribute xml:lang {text}, text},
   element author {
    attribute id {text},
    element name {text},
    element born {text},
    element dead {text}?}*,
   element character {
    attribute id {text},
    element name {text},
    element born {text},
    element qualification {text}}*
  } +
 }
